The expression of the rpoE operon is fine-tuned by the internal rseAp promoter in Salmonella enterica serovar Typhimurium

Biologia ◽  
2010 ◽  
Vol 65 (6) ◽  
Author(s):  
Dagmar Homerova ◽  
Bronislava Rezuchova ◽  
Henrieta Skovierova ◽  
Jan Kormanec
Keyword(s):  
Sigma Factor ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Consensus Sequence ◽  
Coding Region ◽  
Gene Encoding ◽  
In Vivo Experiments ◽  
Envelope Stress ◽  
Serovar Typhimurium

AbstractThree promoters, located upstream of the rpoE gene encoding an extracytoplasmic sigma factor σ E, direct expression of the rpoE operon (rpoE, rseA, rseB, rseC) in Salmonella enterica serovar Typhimurium (S. Typhimurium). One of them, rpoEp3, has been found to be directly recognized by RNA polymerase containing sigma factor σ E. Using the Northern blot analysis we detected a complex pattern of transcripts indicating an internal promoter in the coding region of the rpoE gene. The promoter, rseAp, has been located by S1 mapping analysis. Its proposed −10 and −35 elements with 15 intervening nucleotides exhibited high similarity with the consensus sequence of σ E promoters, suggesting the direct dependence of rseAp upon σ E. Activity of rseAp increased towards stationary phase, after heat shock, cold shock, and in the presence of artificially induced rpoE expression, the conditions previously shown to activate σ E-dependent promoters. In vivo experiments revealed increase of the rseAp activity during growth and confirmed its clear dependence upon σ E. The proposed role of the internal rseAp promoter is to facilitate a feedback control of σ E level after the envelope stress is removed.

scholarly journals Effect of Inactivation of degS on Salmonella enterica Serovar Typhimurium In Vitro and In Vivo

2005 ◽  
Vol 73 (1) ◽  
pp. 459-463 ◽  
Author(s):  
Gary Rowley ◽  
Andrew Stevenson ◽  
Jan Kormanec ◽  
Mark Roberts
Keyword(s):  
Sigma Factor ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Wild Type ◽  
Alternative Pathways ◽  
E Coli ◽  
Mammalian Tissues ◽  
Serovar Typhimurium

ABSTRACT The alternative sigma factor (RpoE σE) enables Salmonella enterica serovar Typhimurium to adapt to stressful conditions, such as oxidative stress, nutrient deprivation, and growth in mammalian tissues. Infection of mice by Salmonella serovar Typhimurium also requires σE. In Escherichia coli, activation of the σE pathway is dependent on proteolysis of the anti-sigma factor RseA and is initiated by DegS. DegS is also important in order for E. coli to cause extraintestinal infection in mice. We constructed a degS mutant of the serovar Typhimurium strain SL1344 and compared its behavior in vitro and in vivo with those of its wild-type (WT) parent and an isogenic rpoE mutant. Unlike E. coli degS strains, the Salmonella serovar Typhimurium degS strain grew as well as the WT strain at 42°C. The degS mutant survived very poorly in murine macrophages in vitro and was highly attenuated compared with the WT strain for both the oral and parenteral routes of infection in mice. However, the degS mutant was not as attenuated as the serovar Typhimurium rpoE mutant: 100- to 1,000-fold more degS bacteria than rpoE bacteria were present in the livers and spleens of mice 24 h after intraperitoneal challenge. In most assays, the rpoE mutant was more severely affected than the degS mutant and a σE-dependent reporter gene was more active in the degS mutant than the rpoE strain. These findings indicate that degS is important for activation of the σE pathway in serovar Typhimurium but that alternative pathways for σE activation probably exist.

scholarly journals opdA, a Salmonella enterica Serovar Typhimurium Gene Encoding a Protease, Is Part of an Operon Regulated by Heat Shock

2000 ◽  
Vol 182 (2) ◽  
pp. 518-521 ◽  
Author(s):  
Christopher A. Conlin ◽  
Charles G. Miller
Keyword(s):  
Escherichia Coli ◽  
Heat Shock ◽  
Sigma Factor ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Temperature Shift ◽  
Open Reading Frame ◽  
Gene Encoding ◽  
Reading Frame ◽  
Serovar Typhimurium

ABSTRACT The opdA (prlC) gene of Salmonella enterica serovar Typhimurium and Escherichia coliencodes the metalloprotease oligopeptidase A (OpdA). We report thatopdA is cotranscribed with a downstream open reading frame,yhiQ. Transcription of this operon is induced after a temperature shift (30 to 42°C), and this induction depends on the heat shock sigma factor encoded by the rpoH(htpR) gene.

scholarly journals Type 1 Fimbriae of Salmonella enterica Serovar Typhimurium Bind to Enterocytes and Contribute to Colonization of Swine In Vivo

2003 ◽  
Vol 71 (11) ◽  
pp. 6446-6452 ◽  
Author(s):  
Carrie Althouse ◽  
Sheila Patterson ◽  
Paula Fedorka-Cray ◽  
Richard E. Isaacson
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Phase Variation ◽  
Gene Encoding ◽  
Type 1 Fimbriae ◽  
Systemic Spread ◽  
Serovar Typhimurium ◽  
Asymptomatic Infections

ABSTRACT Salmonella enterica serovar Typhimurium strain 798 is a clinical isolate from a pig and is known to be able to cause persistent, asymptomatic infections. This strain also is known to exist in two phenotypes (adhesive and nonadhesive to enterocytes) and can switch between the two phenotypes at a rate consistent with phase variation. Cells in the adhesive phenotype are more readily phagocytosed by leukocytes than nonadhesive cells. Once in a leukocyte, adhesive-phase cells survive while nonadhesive-phase cells die. In the present study, nonadhesive mutants were obtained with the transposon TnphoA. A nonadhesive mutant was selected for study and was shown by electron microscopy not to produce fimbriae. The gene encoding the adhesin was cloned and sequenced. Based on its sequence, the adhesin was shown to be FimA, the major subunit of type 1 fimbriae. The nonadhesive mutant was attenuated in its ability to colonize both mouse and pig intestines, but remained capable of systemic spread in mice. The nonadhesive mutant was phagocytosed to the same extent as parental cells in the adhesive phase and then survived intracellularly. These results demonstrated that type 1 fimbriae were important for attachment to enterocytes and promoted intestinal colonization. However, they were not important in promoting phagocytosis or intracellular survival.

scholarly journals Attenuation of Salmonella enterica Serovar Typhimurium by Altering Biological Functions of Murein Lipoprotein and Lipopolysaccharide

2005 ◽  
Vol 73 (12) ◽  
pp. 8433-8436 ◽  
Author(s):  
A. A. Fadl ◽  
J. Sha ◽  
G. R. Klimpel ◽  
J. P. Olano ◽  
C. L. Galindo ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Biological Functions ◽  
Double Knockout ◽  
In Vivo Models ◽  
Background Strain ◽  
Knockout Mutants ◽  
Serovar Typhimurium

ABSTRACT We constructed Salmonella enterica serovar Typhimurium double-knockout mutants in which either the lipoprotein A (lppA) or the lipoprotein B (lppB) gene was deleted from an msbB-negative background strain by marker exchange mutagenesis. These mutants were highly attenuated when tested with in vitro and in vivo models of Salmonella pathogenesis.

scholarly journals Contribution of the Cpx envelope stress system to metabolism and virulence regulation in Salmonella enterica serovar Typhimurium

PLoS ONE ◽  
2019 ◽  
Vol 14 (2) ◽  
pp. e0211584 ◽  
Author(s):  
Sivaraman Subramaniam ◽  
Volker S. Müller ◽  
Nina A. Hering ◽  
Hans Mollenkopf ◽  
Daniel Becker ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Stress System ◽  
Virulence Regulation ◽  
Envelope Stress ◽  
Serovar Typhimurium

scholarly journals The enzyme phosphoglucomutase (Pgm) is required by Salmonella enterica serovar Typhimurium for O-antigen production, resistance to antimicrobial peptides and in vivo fitness

Microbiology ◽  
2009 ◽  
Vol 155 (10) ◽  
pp. 3403-3410 ◽  
Author(s):  
G. K. Paterson ◽  
D. B. Cone ◽  
S. E. Peters ◽  
D. J. Maskell
Keyword(s):  
Antimicrobial Peptides ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Live Attenuated Vaccine ◽  
Antigen Production ◽  
O Antigen ◽  
Serovar Typhimurium

The enzyme phosphoglucomutase (Pgm) catalyses the interconversion of glucose 1-phosphate and glucose 6-phosphate and contributes to glycolysis and the generation of sugar nucleotides for biosynthesis. To assess the role of this enzyme in the biology of the pathogen Salmonella enterica serovar Typhimurium we have characterized a pgm deletion mutant in strain SL1344. Compared to SL1344, SL1344 pgm had impaired growth in vitro, was deficient in the ability to utilize galactose as a carbon source and displayed reduced O-antigen polymer length. The mutant was also more susceptible to antimicrobial peptides and showed decreased fitness in the mouse typhoid model. The in vivo phenotype of SL1344 pgm indicated a role for pgm in the early stages of infection, most likely through deficient O-antigen production. Although pgm mutants in other pathogens have potential as live attenuated vaccine strains, SL1344 pgm was not sufficiently attenuated for such use.

scholarly journals Aspartic Peptide Hydrolases in Salmonella enterica Serovar Typhimurium

2001 ◽  
Vol 183 (10) ◽  
pp. 3089-3097 ◽  
Author(s):  
Rachel A. Larsen ◽  
Tina M. Knox ◽  
Charles G. Miller
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Gene Encoding ◽  
E Coli ◽  
Mutant Strains ◽  
Serovar Typhimurium ◽  
Measurable Rate ◽  
Mature Enzyme ◽  
Aminopeptidase A ◽  
Peptide Hydrolases

ABSTRACT Two well-characterized enzymes in Salmonella entericaserovar Typhimurium and Escherichia coli are able to hydrolyze N-terminal aspartyl (Asp) dipeptides: peptidase B, a broad-specificity aminopeptidase, and peptidase E, an Asp-specific dipeptidase. A serovar Typhimurium strain lacking both of these enzymes, however, can still utilize most N-terminal Asp dipeptides as sources of amino acids, and extracts of such a strain contain additional enzymatic activities able to hydrolyze Asp dipeptides. Here we report two such activities from extracts of pepB pepEmutant strains of serovar Typhimurium identified by their ability to hydrolyze Asp-Leu. Although each of these activities hydrolyzes Asp-Leu at a measurable rate, the preferred substrates for both are N-terminal isoAsp peptides. One of the activities is a previously characterized isoAsp dipeptidase from E. coli, the product of theiadA gene. The other is the product of the serovar Typhimurium homolog of E. coli ybiK, a gene of previously unknown function. This gene product is a member of the N-terminal nucleophile structural family of amidohydrolases. Like most other members of this family, the mature enzyme is generated from a precursor protein by proteolytic cleavage and the active enzyme is a heterotetramer. Based on its ability to hydrolyze an N-terminal isoAsp tripeptide as well as isoAsp dipeptides, the enzyme appears to be an isoAsp aminopeptidase, and we propose that the gene encoding it be designated iaaA (isoAsp aminopeptidase). A strain lacking both IadA and IaaA in addition to peptidase B and peptidase E has been constructed. This strain utilizes Asp-Leu as a leucine source, and extracts of this strain contain at least one additional, as-yet-uncharacterized, peptidase able to cleave Asp dipeptides.

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